This application claims priority to Italian Application No. M099A000220 filed Oct. 8, 1999, the disclosure of which is incorporated herein by reference.
The present invention regards a universal traversing assembly for legs of cranes, or the like or mobile structures of other kinds.
Conventional traversing assemblies comprise one or more platforms which are fitted at the bottom of the legs of the crane or mobile structure and have a plurality of supporting wheels, some of which are driving wheels and some of which are driven wheels; said wheels are actuated by electric motors, or motors of another type, with conventional transmission systems interposed and are made to roll on rails fixed to the ground.
These traversing assemblies are not free from drawbacks, including the fact that the rails on which the crane is to be arranged generally predate the crane, and therefore might not be adapted to support that specific crane model that is used.
In particular, the gauge of the track, i.e. the distance between the two rails on which the pairs of mutually opposite legs rest, is often too small with respect to the dimensions of the crane, the balance of which is therefore precarious and unsteady.
In order to ensure stability, and hence safety of the operators and protect the integrity of the loads being carried, it is necessary to ballast the crane with additional weights, accordingly increasing the stress affecting the movement elements.
Another drawback consists in that the rails fixed to the ground have a preset position and length which, as such, cannot meet all the requirements for the movement of the cranes that arise in the various operating conditions, and long and expensive disassembly/reassembly work is necessary in order to modify them.
Moreover, conventional traversing assemblies use a large number of wheels, even a dozen, and this merely increases the constructive complexity, the large space occupation and the unevenness of operation.
The aim of the present invention is to eliminate the above noted drawbacks of conventional types of traversing assembly by providing a universal traversing assembly for legs of cranes or the like which allows each leg to perform a complete and independent traversing motion, to exactly size the gauge between the rails so as to always have structures stable and balanced without having to ballast them, to use the crane on any terrain, to render the traversing motion of the crane independent of long, fixed and existing rails and to modify the position and length of the rails according to the different operating conditions, without requiring work for modification, assembly and disassembly thereof.
An object of the present invention is to allow to place and use the crane in sites different from the initial ones, if this need arises due to war or other events, by rendering the traversing motion of the crane independent of the rails.
Within the scope of this aim, another object of the present invention is to achieve the above aim and object with a structure which is simple, relatively easy to provide in practice, safe in use, effective in operation, and relatively low in cost.
These and other objects are achieved by the present universal traversing assembly for legs of cranes or the like, comprising a platform provided with a plurality of driving wheels and supporting wheels which are aligned and are adapted to roll on a long underlying rail for the traversing motion of the leg, characterized in that it comprises: a box-like tunnel which rests on the ground, is open in an upward region, and has a portion of the rail fixed to its base; at least one pair of idler wheels, which are freely mounted on the platform, are mutually coaxial and are arranged below a pair of upper guides fixed on the tunnel at the upper opening; a rack which is fixed to the side of the rail portion and is adapted to mesh with pinions which are rigidly coupled and coaxial with respect to the driving wheels; at least one motorization assembly which is rigidly coupled to the platform and is coupled to at least one of said driving wheels and pinions; at least one stabilizer comprising at least one ground resting foot which has an adequate surface, can slide vertically and is adapted to move from a lowered configuration for supporting the leg to a raised inactive configuration, in said supporting configuration the tunnel being raised from the ground and the pinions being adapted to cause the traversing motion of the tunnel with respect to the leg, in the inactive configuration the tunnel resting on the ground and the driving wheels being adapted to cause the traversing motion of the leg with respect to the tunnel.